Organic salt compositions in extraction processes

ABSTRACT

Novel solid salt compositions are described containing, for example, tetraaryl- and triarylaralkyl-phosphonium and arsonium cations and tetraaryl- and tetraaryloxy-boranates and aluminates and polyanionic metal oxide surfaces, for example, as anions. The salts are useful for extracting aromatics and olefins from paraffinic hydrocarbon and aqueous liquid feedstreams, and from vapor and gas feedstreams by absorption.

BACKGROUND OF THE INVENTION

This invention relates to a process for the extraction of aromatics fromprocess gas streams containing various organic components such as tailgas streams from catalytic cracking, the hydrogen stream from catalyticreforming of naphthas, exit gas streams from petrochemical processingreactors, and the like. More particularly, this invention is concernedwith the use of organic salts, in particular, quaternary organicammonium, phosphonium, and arsonium salts with inorganic and organicanions, including halides and pseudohalides, as well as organicquaternary boranates, borates and aluminates as absorption agents, bothalone and supported, for the organic or some of the organic componentsin the process gas streams, even at quite high temperatures. Because ofthe non-volatility of these materials as salts and their low solubilityin hydrocarbon or polar liquids, these salts are also usable asselective sorbants for extraction of aromatics and other polar organicsat lower temperatures when contacted with liquid process streams orwaste water streams at lower temperatures. Such salts show theexceptionally low volatilities of salts, essentially nil, thus allowingtheir contact with large amounts of gases flowing at high rates withoutsignificant losses and facilitating the recovery of extractate orabsorbate. The polarity of the materials as salts and their very largesizes and the essentially spherical shapes of the component ions makethe materials essentially insoluble and such melting, as may take place,only seems to allow the materials to become tacky or semi-solid underoperable absorption conditions. The materials have the exceptionalthermal stability for the high temperature conditions and do notsteam-distill as do more conventional organic absorbants.

In certain instances, it is desirable to remove organics to preventpollution of the air and water. In other instances, it is desirable toselectively remove and recover aromatics or olefins from gas streamswhich are to be used as fuel for burning and which are too dilute forrecovery by conventional means, and thus, the aromatics or olefins arewasted. In other instances, the hydrocarbon gases in the hydrogenoff-gas from catalytic naphtha reforming are undesirable impurities andpresent absorption methods are less than entirely efficient.Furthermore, there are petrochemical gas streams where olefins arepresent in gas streams and it is desirable for selective recovery forrecycle, but they are present in such dilute state that present methodsare relatively rarely used and considerable quantities are lost to usesas fuel. Yet further liquid process feed streams are instances where thepresence of trace aromatics or olefins can poison process catalysts, asin paraffin isomerization, and removal of the trace polar contaminantsis most desirable and necessary, but present absorption and extractionmethods are less than adequate and the usual feed preparation involvesan expensive exhaustive hydrogenation step.

SUMMARY OF THE INVENTION

By contrast, the solid organic salts of the present invention have theunique physical and chemical properties which allow the above problemsto be solved by simple and straightforward selective absorption of polarorganics or organics in general, from liquid hydrocarbon and waterstreams or from dilute gas streams at low or high temperatures, evenhigh temperatures where conventional organics are of little value asabsorbants. The organic salts of this invention are easily synthesizedfrom readily available starting materials and have very high thermal andchemical stability. They can be readily separated from extractatematerials by steam stripping or similar such procedures and theextractate then recovered in a more concentrated form, relative to theoriginal feedstream.

According to this invention, there is provided a composition of matter,being a solid salt, of the formula:

    [C] [A]

wherein [C] is a monovalent or divalent cation selected from the groupconsisting of the formulae:

    [R.sub.4 Q]

    [R.sub.3 R'Q]

    [R.sub.3 Q-L-QR.sub.3 ], and

[A] is a monovalent or divalent anion or a polyanionic metal oxideselected from the group consisting of the formulae:

    [R".sub.4 M]

    [AS]

    [R".sub.3 M-L'-MR".sub.3 ]

wherein Q is independently N, P or As;

R is independently selected from the group consisting of phenyl,naphthyl, biphenylyl, and their monochloro and monomethyl derivatives;

R' is selected from the group consisting of benzyl, naphthylmethyl, andtheir monochloro and monomethyl derivatives; linear and branched C₆ -C₁₂alkyl; cyclopentyl, cyclohexyl, adamantyl, bicyclooctyl, theirmonomethyl, dimethyl, partially fluorinated and partially chlorinatedderivatives;

R" is independently selected from the group consisting of phenyl,naphthyl, phenoxy, naphthoxy, and their methyl, polymethyl, chloro,polychloro, fluoro and polyfluoro derivatives;

L is --CH₂ --(p--C₆ H₄)-CH₂ --;

L' is p-C₆ H₄ ;

M is B or Al;

[AS] is a solid polyanionic metal oxide in which the metal isindependently selected from the group consisting of Al, Si, Ti, Zr, Th,Hf, W, B and mixtures thereof; and wherein the number of cations andanions are sufficient to render the salt electrically neutral.

Preferred embodiments of the cation are where Q is P, [C] is [R₄ Q], [R₄P] and Ph₄ P.

Preferred embodiments of the anion [A] are [R"₄ M], wherein M is B orAl, and wherein at least one R" is aryloxy, and preferably all four R"radicals are aryloxy, or [AS], wherein the metal of the metal oxide ofthe [AS] salt is Al or Si. Most preferably, the metal of the metal oxideof [AS] is Al.

Where the anion is other than [AS], preferably the composition containsone cation and one anion. Where the anion is [AS], the composition is ametal oxide having the defined cations absorbed onto the surfaceproducing an electrically neutral composition.

Further provided is a process for extracting aromatic and olefinichydrocarbons and organic hydrocarbons from mixed liquid or gaseousfeedstreams, containing paraffins comprising contacting said feedstreamswith the compositions defined and described above at a temperature inthe range of about 20°-500° C.

Also provided is a composition, being a solid salt, of the formula:

    [C] [A]

wherein [C] is a monovalent or divalent cation of the formula:

    [R.sub.4 Q]

wherein Q is P or As;

R is an aryl radical independently selected from the group consisting ofphenyl, naphthyl, monochloro and monomethyl derivatives thereof; and

[A] is an anion independently selected from the group consisting of theformulae:

    [R".sub.4 M]

    [R.sub.3 "M-L'-MR".sub.3 ]

    [AS],

wherein R" is independently selected from the group consisting ofphenyl, naphthyl, phenoxy, naphthoxy, and their methyl, polymethyl,chloro, polychloro, fluoro and polyfluoro derivatives:

M is B or Al;

L' is p-C₆ H₄ ;

[AS] is a solid polyanionic metal oxide in which the metal isindependently selected from the group consisting of Al, Si, Ti, Zr, Hf,Th, W and B, and mixtures thereof, wherein the number of cations andanions is sufficient to render the salt electrically neutral.

Preferred is wherein Q is P, [A] is [AS], and the metal of metal oxideis Al. Also preferred is the composition in which [A] is [R"₄ M] M isAl, and all four R" radicals are phenoxy.

Furthermore, there is provided a process for selectively absorbingolefins and aromatics from gaseous feedstreams containing paraffinscomprising contacting said feedstreams with the above-describedcomposition, in the immediately preceding paragraph, at a temperature inthe range of 250°-500° C.

DESCRIPTION OF THE INVENTION

Representative examples of the quaternary and other solid anions usefulin the highest temperature absorptions and extractions includetetraphenylboranate [BPh₄ ], tetraphenylaluminate [AlPh₄ ],tetraphenoxyaluminate [(Ph-O)₄ Al], tetraphenoxyboranate [(Ph-O)₄ B],phenoxytriphenylboranate [(Ph-O-)BPh₃ ], phenoxytriphenylaluminate[(Ph-O-)AlPh₃ ], pentafluorophenyltriphenylboranate [(C₆ F₅)BPh₃ ],pentachlorophenyltriphenylaluminate [(C₆ Cl₅)AlPh₃ ],p-methylphenyltriphenylboranate [p-CH₃ (C₆ H₄)BPh₃ ],p-bis(triphenylboranate)benzene, and high surface area metal oxides [AS]including gamma alumina [gamma-Al₂ O₃ ], silica [SiO₂ ], zirconia onalumina [gamma-Al₂ O₃ -ZrO₂ ], aluminosilicates [Al₂ O₃ -SiO₂ ],titania-silica [TiO₂ -SiO₂ ], and the like.

Novel quaternary anions among those above include those with phenoxy andsubstituted phenoxy R" radicals, in particular the anions [A] of formula[R"₄ M] wherein R" is an aryl or aryloxy radical independently selectedfrom the group consisting of phenyl, naphthyl, phenoxy, naphthoxy, andtheir methyl, polymethyl, chloro, polychloro, fluoro and polyfluoroderivatives; M is B or Al; and preferably where at least one R" ischosen from among those with oxy linkages to the heteroatom M. Suchnovel quaternary anions are preferred because the aryloxyfunctionalities are particularly inexpensive to produce relative to thearyl functionalities, although their stabilities are comparable. Mostpreferred is where all four R" radicals are aryloxy.

Preparations of the novel aryloxy-substituted anions [A] are by quitemodern techniques, a fact which again emphasizes their unexpected naturesince they were of a group not previously considered to besynthesizeable. The key aspects to their preparations involve the modernuse of polar non-hydroxylic solvents and the necessity to avoid eventraces of water or protonated oxygens in the preparation system. Thefollowing examples use the phenoxide R" radical as the example giving anillustrative example of the best mode of carrying out this preparativeinvention, as contemplated by us, and should not be construed as being alimitation on the scope or spirit of the instant invention. The equationbelow describes the overall reaction of the two readily availablestarting materials.

    Na.sup.+ (ether ligands) .sup.-O-Ph+BPh.sub.3 →Na.sup.+ (ether ligands) [(Ph-O)-BPh.sub.3 ]

The sodium phenoxide and triphenylborane, sometimes calledtriphenylboron were combined in one-to-one molecular ratio in ethersolution at the reflux temperature of the ether, with both materialsbeing slowly brought together as dilute solutions from separate Soxhletextractors, the salt then crystallizing from the solution as formed. Thepreparation experiment was done both with tetrahydrofuran and withdimethylether as solvent, the latter appearing to function best. Thesolvents and starting materials were exceptionally well dried anddeprotonated by standard but exhaustive techniques, e.g., distillationof solvents from LiAlH₄ under nitrogen, flame drying glassware underdried N₂ flow, vacuum system sublimation of Ph₃ B in the presence oftert-butyllithium, vacuum transpiration of excess PhOH and H₂ O from theNaOPh, and drying and dehydrogenation of the inert N₂ under which thereaction was run by passing it through a triethylaluminum-treatedgamma-Al₂ O₃ bed in a quartz tube furnace at 120° C. Workup of thepreparations is not sensitive and simply involves separation of thecrystalline material, which retained considerable ether from the solventas ligands for the Na⁺ ions. The retained solvent was inconsequentialfor the subsequent uses in the preparations of the salts which containthe organic cations as well as organic anions. Other preparationsinvolved similar procedures on other available starting materials suchas triphenoxyborate (PhO)₃ B, triphenoxyaluminate (PhO)₃ Al,triphenylaluminum Ph₃ Al, etc. Elemental analyses were utilized asproofs of structure and were required to fit those theoreticallynecessary within experimental error.

The remaining organic anions are prepared by very similar butcomplementary means by contacting in one to one molecular ratioarylithium compounds in inert solution under inert atmosphere conditionswith the appropriate tertiary boron or aluminum material with theproduct crystallizing out, filtering to remove solvent, and thenappropriate drying. The equation of the example below shows thepreparation of lithium p-methylphenyltriphenylboranate in 1:1benzene-THF as solvent.

    Li--(C.sub.6 H.sub.4)--p--CH.sub.3 +BPh.sub.3 →Li.sup.⊕ p--CH.sub.3 --C.sub.6 H.sub.4 --B.sup.⊖ Ph.sub.3

The same sort of inert atmosphere and apparatus and solvent dryingprecautions are taken in this group of anion preparations as in thepreparation of the abovedescribed novel quaternary organic anions exceptin the product workup where the materials, aside from simple absorptionof water, are not air sensitive.

Representative examples of the cations useful in the highest temperatureabsorptions and extractions fit the formula [R₄ Q] and includetetraphenylphosphonium, tetraphenylarsonium,p-methylphenyltriphenylphosphonium, p-chlorophenyltriphenylphosphonium,p-methylphenyltriphenylarsonium, p-chlorophenyltriphenylarsonium and1-naphthyltriphenylarsonium ions, the group of highest thermalstability. This highest thermal stability is present because onlyaromatic carbons are attached to the heteroatom Q, with the aromaticπ-electron clouds stabilizing the ⊕ charge.

Representative examples of the cations useful in the high temperatureabsorptions and extractions, but not limited to the highest temperaturerange, include tetraphenylphosphonium, tetraphenylarsonium,p-methylphenyltriphenylarsonium, p-chlorophenyltriphenylarsonium,1-naphthyltriphenylarsonium, p-methylphenyltriphenylphosphonium,p-chlorophenyltriphenylphosphonium, benzyltriphenylammonium,benzyltriphenylphosphonium, benzyltriphenylarsonium,tetrabenzylammonium, p-methylbenzyltribenzylammonium,p-methylbenzyltriphenylphosphonium, p-chlorobenzyltriphenylphosphonium,p-methylbenzyltriphenylarsonium, p-chlorobenzyltriphenylarsonium,α,α-bis(triphenylphosphonium)-p-xylene, adamantyltriphenylphosphonium,adamantyltriphenylarsonium, 2-ethylhexyltriphenylphosphonium, and3-chloro-4-fluorocyclopentyltriphenylphosphonium ions, the group ofrelatively high thermal stability. The thermal and chemical stability isquite high due to three aromatic R radicals attached to the heteroatomQ, but the aliphatic fourth R' is a weaker bond to the Q atom.

By the term "partially fluorinated" and "partially chlorinated" is meantless than the total number of fluoro and chloro groups to achieve theperhalogenated structure.

The following non-limiting examples are illustrative of the best mode ofpreparation of the solid organic salts. The quaternary organic cationsare prepared by means of the reaction of a tertiary amine, phosphine, orarsine with an alkyl or aryl halide, sulfate, phosphate, sulfonate, orother such reactive compound. Fluoride is an inappropriate halide, andthe heavier the halide, the better, although more expensive. Toluene-,benzene-, or methanesulfonates and sulfates are quite good. Thematerials in one-to-one molecular ratio are heated together and added asin the following example showing the preparation ofp-methylphenyltriphenylphosphonium bromide by heating at 200° C. forfour weeks without solvent and another four weeks after the addition oftwo volumes of diphenylether as solvent in order to complete thereaction in conventional glass apparatus under a nitrogen atmosphere.The product crystallized out upon cooling and the solvent removed fromthe crystals by filtration and drying in a N₂ flow at elevatedtemperatures (˜100° C.). ##STR1##

The general reaction for preparation of the combination salts withquaternary organic cations and quaternary organic anions is novel,albeit somewhat difficult to accomplish without occluding as impuritiesthe relatively insoluble starting material salts of the types describedabove. The preparation of the combination salts is effected bycontacting in one-to-one molecular ratio the quaternary organic cationsand anions as their, for instance, halide and alkali metal saltsrespectively, in dilute dichloromethane solution, the salts being slowlyintroduced by simultaneous Soxhlet extraction of the thoroughly driedprecursor salts in conventional apparatus. The product salt crystallizesout as a mixture of separate substances which, after filtration toremove solvent, then is susceptible to facile separation by a simplewater wash to remove the inorganic salt before final drying of thepurified organic salt. The example of the preparation ofp-methylphenyltriphenylphosphonium p-methylphenyltriphenylboranate (alsocalled p-tolyltriphenylphosphonium p-tolyltriphenylboranate) is shown inthe following equation:

    p--CH.sub.3 (C.sub.6 H.sub.4)P.sup.⊕ Ph.sub.3 Br.sup.⊖ +p--CH.sub.3 (C.sub.6 H.sub.4)B.sup.⊖ Ph.sub.3 Li.sup.⊕ →LiBr+[p--CH.sub.3 (C.sub.6 H.sub.4)P.sup.⊕ Ph.sub.3 ][p--CH.sub.3 (C.sub.6 H.sub.4)B.sup.⊖ Ph.sub.3 ]

Such large combination salts of large quaternary organic cations andlarge quaternary organic anions are unique and previously unknown, eventhough some of the component parts were known and used for otherpurposes.

The preparation of the solid quaternary organic salts of the generalformulae [R₄ Q][AS], [R₃ R'Q][AS] and [R₃ Q-L-QR₃ ][AS] all fall intothe same general procedure, a variation of the above procedure for thepreparation of the similar salts with quaternary organic anions. Thesesalt materials are prepared from preferably, but not limited to, highsurface area polyanionic metal oxide supports, preferably above 100 m²/g, and most preferably above 150 m² /g, by deposition of the quaternaryorganic cation as its simple salt, e.g., halide, sulfonate, and thelike, onto it from dilute solution. The actual procedure for the examplebelow is illustrated: ##STR2## The dried p-tolyltriphenylphosphoniumbromide is deposited from dilute solution by Soxhlet extraction indichloromethane (methylene chloride) onto the prepared metal oxidesupport. The support was prepared by impregnating by standard incipientwetness impregnation techniques, 100 g of a γ-Al₂ O₃ catalyst support of203 m² /g surface area and no measurable sodium or alkali metal content,with 7.7 mmoles of zirconium n-propoxide in n-propanol. This materialwas dried and then steamed at 150° C. for 16 hours and then dried in aflow of dry air at the same temperature for 4 hours before thedeposition of the quaternary organic salt. The quantity of 10 mmoles ofthe phosphonium bromide was deposited by the Soxhlet extraction with thezirconia-alumina within the pot of refluxing dichloromethane solvent.After separation of the solvent and drying, the solid material wassteamed for 16 hours at 200° C. and then for 8 hours at 400° C. toeliminate any remaining HBr from the sorbant.

More particular comments pertaining to the general compositional formuladefined in the Summary of The Invention are that preferred embodimentsof the composition include where Q is phosphorous and M is boron oraluminum and particularly preferred is aluminum.

Preferred is wherein the anion [A] is [AS] comprising a polyanionicmetal oxide and wherein the metal in said [AS] is preferably Al or Siand most preferably Al.

The cation [C] preferably is [R₄ Q] and wherein Q is P or As, and mostpreferably P. Particularly preferred as [C] is [R₄ P] wherein R is aryland most particularly Ph₄ P.

Representative examples of compositions of the subject invention aretetraphenylphosphonium tetraphenylboranate, tetraphenylphosphoniump-tolyltriphenylboranate, tetraphenylphosphonium tetraphenoxyboranate,tetraphenylphosphonium phenoxytriphenylaluminate, tetraphenylphosphoniumtetraphenoxyaluminate, tetraphenylphosphoniump-bis(triphenylboranate)benzene, tetraphenylphosphoniumtetraphenylaluminate [Ph₄ P][Ph₄ Al], tetraphenylphosphoniumpentafluorophenyltriphenylboranate, tetraphenylphosphoniumtetrakis(pentachlorophenoxy)aluminate, tetraphenylphosphoniumtetrakis(pentafluorophenoxy)boranate, tetraphenylphosphoniumzirconia-aluminosilicate, tetraphenylphosphonium alumina (or aluminate),tetraphenylphosphonium aluminosilicate, tetraphenylphosphonium silicate,tetraphenylphosphonium aluminotitanate, tetraphenylphosphoniumtitania-alumina, tetraphenylphosphonium titania-aluminosilicate,tetraphenylphosphonium titania (or titanate), tetraphenylphosphoniumboriaalumina, tetraphenylphosphonium zirconium-alumina,tetraphenylarsonium tetraphenylboranate, tetraphenylarsoniumtetraphenylaluminate, tetraphenylarsonium tetraphenoxy aluminate,tetraphenylarsonium zirconia-alumina (or zirconia-aluminate),p-chlorophenyltriphenylphosphonium tetraphenylboranate,p-chlorophenyltriphenylphosphonium gamma aluminate,p-chlorophenyltriphenylphosphonium silicate, p-tolyltriphenylphosphoniumtetraphenylboranate, p-tolyltriphenylphosphonium zirconia-alumina,2-naphthyltriphenylarsonium tetraphenylboranate,p-biphenylyltriphenylphosphonium tetrakis(p-biphenylylaluminate),p-biphenylyltriphenylphosphoniump-trifluoromethylphenyltriphenylboranate,6-methyl-2-naphthyltriphenylarsonium tungstia-alumina,tetrakis(p-biphenylyl)phosphonium thoria-alumina, tetrakis(p-biphenylyl)phosphonium hafnia-alumina, benzyltriphenylphosphoniumtetraphenylboranate, benzyltriphenylphosphoniump-tolyltriphenylboranate, benzyltriphenylphosphoniumphenoxytriphenylboranate, benzyltriphenylphosphoniumtetraphenoxyboranate, benzyltriphenylphosphonium tetraphenylaluminate,benzyltriphenylphosphonium tetraphenoxyaluminate,benzyltriphenylphosphonium phenoxytriphenylaluminate,benzyltriphenylphosphonium p-bis(triphenylboranate)benzene,benzyltriphenylphosphonium tetrakis(pentachlorophenoxy)aluminate,benzyltriphenylphosphonium p-chlorophenyltriphenylboranate,benzyltriphenylphosphonium alumina, benzyltriphenylphosphonium titania,benzyltriphenylphosphonium silica, benzyltriphenylphosphoniumaluminosilicate, benzyltriphenylphosphonium zirconia-aluminosilicate,benzyltriphenylphosphonium titaniaaluminosilicate,benzyltriphenylphosphonium boria-alumina, benzyltriphenylphosphoniumtitania-alumina, benzyltriphenylphosphonium zirconia-alumina,benzyltriphenylphosphonium aluminum oxyfluoride-alumina,benzyltriphenylarsonium tetraphenylboranate, benzyltriphenylarsoniumtetraphenoxy aluminate, benzyltriphenylarsonium tetraphenoxyboranate,benzyltriphenylarsonium zirconia-alumina, benzyltriphenylammoniumtetraphenylboranate, tetrabenzylammonium tetraphenylboranate,tetrabenzylammonium tetraphenoxyaluminate,tribenzyl-p-methylbenzylammonium tetraphenylboranate,p-methylbenzyltriphenylphosphonium tetraphenylboranate,p-methylbenzyltriphenylphosphonium p-tolyltriphenylboranate,p-methylbenzyltriphenylphosphonium zirconia-aluminosilicate,bis(triphenylphosphonium)p-xylylene tetraphenylboranate,p-chlorobenzyltriphenylphosphonium tetraphenylboranate,tetra-p-tolylphosphonium tetraphenylboranate, 2- L-ethylhexyltriphenylphosphonium tetraphenylboranate,2-ethylhexyltriphenylphosphonium tetraphenoxyaluminate,1-adamantyltriphenylphosphonium tetraphenylboranate,(p-tolyl)-p-benzyltriphenylphosphonium tetrakis(trichlorophenoxy)aluminate, and the like.

Particularly preferred examples are tetraphenylphosphoniumtetraphenylboranate, tetraphenylphosphonium aluminosilicate,tetraphenylphosphonium tetraphenoxy aluminate, tetraphenylphosphoniumzirconia-alumina, benzyltriphenylphosphonium tetraphenylboranate,benzyltriphenylphosphonium tetraphenoxyaluminate,benzyltriphenylphosphonium aluminosilicate, andbenzyltriphenylphosphonium zirconia-alumina.

The subject compositions are solid salts, and by the term "solid" ismeant that the salts are solid at ambient temperature and substantiallysolid at the temperatures of use, and as such, are not pumpable orpourable except as particles or particulates or slurries, e.g.,fluidized solids; however, they may become somewhat tacky uponabsorption of other organic materials, e.g., during use as absorption orextraction agents.

The unique compounds of the present invention are useful in two noveltypes of related processes. The more thermally stable materials areuseful in high temperature absorption of organics or polar organics fromhot gas phase feedstreams with subsequent recovery of absorbed organicsby steam stripping and condensation. The group of compounds operable forthese high temperature absorptions include those of formulae [R₄ Q][R"₄M], [R₄ Q]₂ [R"₃ M-L'-MR"₃ ], and [R₄ Q][AS]. These materials are alsouseful for extraction and absorption from liquids at both the higher andlower temperatures when the process is operated at at least a pressuresufficient to maintain the feedstream as a liquid. The extraction may bedone in fixed-bed, moving-bed, slurry, or other similar manner inequipment typical for contacting a liquid, vapor, or gas with solidabsorbants or extractants. For best results, effectively, countercurrentcontacting of the feed with the solid extractant in a batch system orcontinuous system is preferred, although these are not to be construedas constituting the limitations of the invention. Likewise, theabsorption of organics, either selectively or nonselectively, can beeffected in essentially similar fixed-bed, moving-bed, fluidized-bed, orraining solids processes in conventional equipment.

The low temperature solid salt extraction and absorption processes canbe accomplished at temperatures from ambient (20° C.) up through about400° C., preferably below 325° C., and most preferably below 250° C. Thehigh temperature solid salt extraction and absorption processes can beaccomplished at temperatures up to about 500° C., but preferably belowabout 450° C. Thus, the range of extraction processes is from 20°-500°C. In both high temperature and low temperature processes, the processmust be conducted at a temperature below the decomposition temperatureof the particular salt or salts in use for the extraction or theabsorption. Generally, for selective aromatics extraction from liquid orgaseous feedstreams, the lowest possible temperatures, compatible withother upstream or downstream processes and the associated economics,should be utilized to obtain maximum selectivity and capacity of thesolid salts due to the necessity of combating the volatility of thearomatic compounds at high temperatures. Likewise, the absorption ofgaseous organics is most preferred at the lowest temperature compatiblewith surrounding processes due to the increasing selectivity andcapacity at lower temperatures because of the necessity of combating thevolatility of the low molecular weight molecules being absorbed.

The feedstreams operable in the processes are liquids, vapors or gasescontaining paraffins at temperatures in the range of about 20°-500° C.

A preferred process is for selectively absorbing olefins and aromaticsfrom gaseous feedstreams containing paraffins comprising contacting saidfeedstreams with the subject composition described herein, wherein Q isP, [A] is [AS] and said metal of said metal oxide is Al and saidtemperature is in the range of 250°-500° C.

The quaternary organic salts of the present invention can be used asmixtures, however, it is quite preferred that they be used as a singleor pure material. This preferred mode of use of the solid salts is indirect contrast with the related mode of use of the less aromatic liquidquaternary organic salts and their use as liquid solvents for extractionof aromatics from paraffinic hydrocarbons for which the preferred modeof use is as mixtures of the salts, either mixtures of cations or anionsor both.

The operation of these solid organic salts as extractants or absorbantsis considerably different than the liquid salt solvent systems, whichfunction by way of mutual solubility of the aromatics and liquid salts,and also different from simple high surface area absorbants such asactivated carbons, etc., which function by absorption onto a surface atactive sites. The solid organic salts of the instant invention functionby accepting guest molecules into the holes within the solid structureand between the ions which make up the salt. The ions have considerablepotential and ability to move aside temporarily to allow the guestmolecules to enter the lattice spaces. Such behavior is in contrast tothe typical clathrate behavior wherein guest molecules can only beincluded into the host molecule crystal lattice during crystallizationof the host substance. Because these quaternary organic salts of thepresent invention have the ability to move enough to allow "dissolution"or "inclusion" of the guest molecules readily into the solid structure,they are much more useful for extraction and absorption than theconventional clathrate separation materials and processes, and likewise,more useful than the less selective carbon absorptions and liquidsolvent extractions.

The large ions of the solid combination quaternary organic salts of thepresent invention are roughly spherical in shape such that each pair ofa cation and anion, a neutral pair, can be considered to be a pair ofspheres, roughly approximating billiard ball models, and the set of suchspheres in a solid crystal also approximating the stacking of billiardball spheres. Such crystal latices have considerable spaces ofparticular volumes, shapes, and positions into which guest molecules canbe put. The fact that these salts accept and release such guestmolecules during the normal course of use is unique to their structureand provides for some additional unique uses and selectivities ofextraction and absorption of organic molecules. Such sets or lattices ofions behave in some ways almost as if they were sieve-like. The organiccation salts of the present invention with the solid metal oxide surfaceanions then can be visualized as if they were a layer or several layersof the spherical cations covering the high surface area support-typeanion, which might thus be approximated as a set of billiard ball typespheres sitting on a group of flat or nearly flat surfaces with theavailable spaces being, not only between the spheres, but also betweenthe spheres and the flat surfaces.

A particularly unique property of the combination quaternary organicsalts and also of the salts of quaternary organic cations with solidsurface anions is their exceptionally modifiable nature, specificallysynthesizeable into the ions during preparation. Parts of the ions canbe changed, enlarged, extended, polarized, etc., simply by substitutingR, R', R", L, and L' groups of different composition, shape, structure,etc. In such manner, the sizes and shapes of the lattice spaces,polarities, hardness or softness and thus interactability withπ-electron clouds of guest molecules, and other such chemical andphysical properties can be specifically tailored to the actual use andprocess intended for the salt.

Consequently, it is clear why the group of organic salts of the presentinvention function better as pure or neat materials rather than asmixtures, with any mixed salt impurities tending to decrease theselectivity and capacities by partially or wholly filling andeliminating some of the void spaces where guest molecules would locateduring extraction or absorption.

The void spaces between and among the organic ions in the instantinvention are tailored for the specific use by choice of radicals on theions. Large chlorine substituents and methyl substituents on thearomatics of the R radicals increase overall size but can give eitherincreased size or decreased size depending on the particularcombinations. Chlorine substituents on R radicals are preferred forselective extraction or absorption of aromatics, olefins, or polarspecies, whereas the use of methyl group substituents on the R radicalsis preferred for paraffinic or general organic absorption or extraction,e.g., methane absorption from H₂ streams. The presence of at least onenon-hydrogen substituent in the R radical of an ion of the salt ispreferred over the solely hydrogen substituted R group salts because ofincreased rates of absorption, extraction and removal of extractate orabsorbate. Conversely, the use of solely hydrogen substituted R and R"radicals of the salts is preferred due to higher thermal and chemicalstability and lower basic costs. The use of aluminum anions is preferreddue to lower basic costs, but the use of boron anions is preferred dueto generally better stability. Phosphonium cations are greatly preferredover those of As and N due to cost and stabilities and ease ofmanufacture, while salts of As are preferred over those of N due tostability. High temperature salts of nitrogen cations are generally notsynthesizeable and operable in the present invention process.

The ease of separation of the extractant or adsorbate from the feedstream and then from the extractate are also very importantcharacteristics that the salts should possess. This characteristic isextremely important when it is desired to reduce the concentration ofaromatic hydrocarbons in the feedstreams to extremely low concentrationsand to avoid any possible contamination of the feedstream with absorbantas in the preparation of feeds for paraffin isomerization. Conventionalliquid solvents such as sulfolane, cannot be reduced to thearomatic-free state because of their volatility. By contrast, theinstant solid organic salts have essentially zero volatility, and arereadily freed of aromatics by stripping, steam distillation, etc., andthey have essentially zero solubility in paraffinic solvents and feedstreams. Complete recovery of aromatic extractate is possible and thusseparation of solvent or chemical intermediate aromatics fromaromatics-rich naphthas are thus also possible.

The phosphonium salts are most preferred because of thier thermal andchemical stability; arsonium salts are less preferred, but are preferredto the least stable ammonium salts. The same order of preference,N<As<P, is also the same order or preference on the basis of costs andease of preparation. When R radicals of derivatives of naphthalene areused, only As and P are usable as the heteroatom of the cation and As isgreatly preferred for steric reasons; the stability of the N cations isentirely unsuitable due to steric crowding. It has been found that theoperable salts for the lower temperature extractions and absorptionscontain R' hydrocarbon radicals in the size range of C₅ to C₁₂, withbranched and cyclic species most preferred.

Only quaternary organic ions, either cations or anions, are suitable foruse in the extraction and absorption processes described herein. Otherorganic anions are generally too unstable thermally and chemically.Likewise, tertiary, secondary, and primary organic cations and anionsare entirely too reactive and unstable to be operable in the describedprocess.

The process feedstream in the process should be clean and havereasonably low molecular weight to avoid contamination of the salts withintractable polymers. Even traces of high molecular weight materials inthe feedstream are to be avoided.

The temperature at which the high temperature extractions andabsorptions can be conducted is in the range of 20°-500° C., butpreferably should be minimized. However, certain types of processes, forexample, absorption of aromatic hydrocarbons from gas streams, are bestrun at higher temperatures in order to obtain adequate rates ofabsorption. Consequently, it is preferred that high temperatureabsorption be effected at about 250° C. or higher and most preferably atabout 325° C. or higher when rates are taken into account so thatcontact times can be minimized.

The compositions of the instant invention, particularly the class ofalkyltriarylphosphonium salts, are also capable of removing aromaticsand even aliphatic hydrocarbons from waste water streams.

Anion surface [AS] is less preferred than the organic anion due to lowerselectivity of extraction toward aromatics relative to paraffinics, butmore preferred due to economy of manufacture and materials cost andcapabilities in process design.

The following non-limiting examples of the extraction and absorptionprocesses are illustrative of the best modes of the invention processand are illustrative of both low and high temperature absorption and lowtemperature extraction. The examples should not be construed as beinglimitations on the scope and spirit of the instant invention.

EXAMPLE 1 High Temperature Absorption

A powder sample of 100 g. of tetraphenylphosphonium tetraphenylboranatewas fluidized in a quartz tube furnace at 425° C. in a stream of a gasmixture of N₂ :CO₂ :CO:H₂ :C₂ H₄ of ratio 6:2:1:1:0.001 at ambientpressure, 755 torr, for the time necessary for 1000 volumes of the gasflow past the fluidized bed. The gas was then switched to H₂ O vapor atthe same temperature and ethylene recovered by condensation andmeasurement by GC and mass spectrometer amounted to 93% of thecalculated theoretical amount.

EXAMPLE 2 High Temperature Absorption

A powder sample (60-150 mesh) of 100 g of p-tolyltriphenylphosphoniumγ-aluminozirconate of BET surface area of 142 m² /g was fluidized asabove but in which the gas stream contained additional methane in anamount equal to that of the ethylene. The amounts of ethylene andmethane recovered were equal to 91% and 24%, respectively.

EXAMPLE 3 Low Temperature Absorption

A 100 g sample of 14/35 mesh sorbant p-chlorophenylphosphoniumγ-aluminate of BET surface area of 168 m² /g was contacted in a fixedbed in a quartz tube furnace with a down-flow gas stream containing N₂:C₆ H₆ :n-C₇ H₁₆ in ratio of 8:1:1 at 250° C. with 100 volumes of gaswith the workup as above. The amounts of benzene and heptane recoveredwere equal to 85% and 11%, respectively, of the calculated theoreticalamounts.

EXAMPLE 4 Low Temperature Absorption

A 100 g sample of 14/35 mesh sorbant p-methylbenzyltriphenylphosphoniumγ-aluminosilicatezirconate of 328 m² /g BET surface area was contactedwith a gaseous feedstream as above in a fixed bed process at 225° C.with 100 volumes of H₂ and CH₄ in a volume ratio of 19:1. Workup asabove, gave recovery of 74% of the calculated theoretical amount ofmethane.

EXAMPLE 5 Low Temperature Extraction

A 100 g sample of powdered tetraphenylphosphoniumtetrakis(pentachlorophenyl)aluminate was slurried with 500 ml. of aliquid feed of benzene and heptane in 1:99 volume ratio at 300° C. at1500 psig N₂ pressure, more than sufficient to maintain the feed as aliquid, and after stirring for 1 hour, the liquid decanted off. Steamstripping of the solids, still maintained at the same temperatureallowed recovery of 88% of the benzene theoretically possible, ascalculated on the basis of that in the original feed.

EXAMPLE 6 Low Temperature Absorption (Extraction)

100 g. of powdered benzyltriphenylphosphonium tetraphenoxyaluminate wereslurried at 35° C. for 2 hours in 5 liters of water containing 650 partsper million benzene and 50 parts per million n-heptane. After separationand workup by N₂ stripping of the solids with dry ice condensation andmeasurement, as described above, 98% of benzene and 99% of n-heptanewere recovered as having been extracted or absorbed from the aqueoussolution, calculated on the basis of that originally present.

What is claimed is:
 1. A composition of matter, being a solid salt, ofthe formula:

    [C] [A]

wherein [C] is a monovalent or divalent cation selected from the groupconsisting of the formulae:

    [R.sub.4 Q]

    [R.sub.3 R'Q]

    [R.sub.3 Q-L-QR.sub.3 ], and

[A] is a monovalent or divalent anion or a solid polyanionic metal oxideselected from the group consisting of the formulae:

    [R".sub.4 M]

    [AS]

    [R".sub.3 M-L'-MR".sub.3 ]

wherein Q is independently N, P or As; R is independently selected fromthe group consisting of phenyl, naphthyl, biphenylyl, and theirmonochloro and monomethyl derivatives; R' is independently selected fromthe group consisting of benzyl, naphthylmethyl, and their monochloro andmonomethyl derivatives; linear and branched C₆ -C₁₂ alkyl; cyclopentyl,cyclohexyl, adamantyl, bicyclooctyl, their monomethyl, dimethyl,partially fluorinated and partially chlorinated derivatives; R" isindependently selected from the group consisting of phenyl, naphthyl,phenoxy, naphthoxy, and their methyl, polymethyl, chloro, polychloro,fluoro and polyfluoro derivatives; L is --CH₂ (p--C₆ H₄)CH₂ --; L' isp-C₆ H₄ ; M is B or Al; [AS] comprises a solid polyanionic metal oxidein which the metal is independently selected from the group consistingof Al, Si, Ti, Zr, Th, Hf, W, B and mixtures thereof; and wherein thenumber of cations and anions are sufficient to render the saltelectrically neutral.
 2. The composition of claim 1 wherein Q isphosphorus.
 3. The composition of claim 1 wherein M is boron.
 4. Thecomposition of claim 1 wherein M is aluminum.
 5. The composition ofclaim 1 wherein the anion [A] is [AS].
 6. The composition of claim 1wherein the metal of the metal oxide of the [AS] is Al.
 7. Thecomposition of claim 1 wherein the metal in [AS] is Al or Si.
 8. Thecomposition of claim 1 wherein [C] is [R₄ Q].
 9. The composition ofclaim 8 wherein [C] is [R₄ P].
 10. The composition of claim 1 wherein atleast one R" in [R"₄ M] is phenoxy, naphthoxy, and their methyl,polymethyl, chloro, polychloro, fluoro and polyfluoro derivatives. 11.The composition of claim 10 wherein all 4 R" radicals in [R"₄ M] areselected from phenoxy, naphthoxy, and their methyl, polymethyl, chloro,polychloro, fluoro, and polyfluoro derivatives.
 12. The composition ofclaim 1 wherein [C] is Ph₄ P.
 13. A composition of matter, being a solidsalt, of the formula:

    [C] [A],

wherein [C] is a monovalent or divalent cation of the formula:

    [R.sub.4 Q]

wherein Q is P or As; R is an aryl radical independently selected fromthe group consisting of phenyl, naphthyl, monochloro and monomethylderivatives thereof; and [A] is an anion independently selected from thegroup consisting of the formula:

    [R".sub.4 M]

    [R".sub.3 M-L'-MR".sub.3 ]

    [AS],

wherein R" is independently selected from the group consisting ofphenyl, naphthyl, phenoxy, naphthoxy, and their methyl, polymethyl,chloro, polychloro, fluoro, polyfluoro derivatives; M is B or Al; L' isp-C₆ H₄ ; [AS] comprises a solid polyanionic metal oxide in which themetal is independently selected from the group consisting of Al, Si, Ti,Zr, Hf, Th, W and B, and mixtures thereof, wherein the number of cationsand anions is sufficient to render the salt electrically neutral. 14.The composition of claim 13 wherein Q is P.
 15. The composition,tetraphenylphosphonium tetraphenyl boronate.
 16. The composition,tetraphenylphosphonium aluminosilicate.
 17. The composition,tetraphenylphosphonium tetraphenoxyaluminate.
 18. The composition,benzyltriphenylphosphonium tetraphenylboranate.
 19. The composition,benzyltriphenylphosphonium tetraphenoxyaluminate.
 20. The composition,benzyltriphenylphosphonium aluminosilicate.